The invention concerns thermoplastic molding compositions and more particularly compositions containing graft polymers
Thermoplastic molding composition characterized in that the polymer proportion soluble in dichloromethane has a c50 value of acrylonitrile of xe2x89xa728 wt. % and a chemical distribution (c90xe2x88x92c10 value) of the acrylonitrile of xe2x89xa75 wt. % is disclosed. The composition is characterized by its improved processability by extrusion and thermoforming.
Thermoplastic resins of the ABS type have been used for many years for the production of all kinds of moulded parts (see e.g. Ullmann""s Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A21, pages 652-653, VCH, Weinheim, 1992).
Apart from injection molding, a common form of processing for such thermoplastic resins is extrusion, the extrusion stage (e.g. production of sheets) often being followed by a thermoforming stage (production of three-dimensional moulded parts).
Materials used for processing by extrusion and thermoforming are required to have good melt elasticity whilst maintaining a good surface finish and good mechanical properties (e.g. toughness) of the thermoformed parts.
Moreover, it is important that the appropriate materials are easily obtainable (production without great technical complexity) and have an uncomplicated constitution (no components that are expensive or difficult to obtain).
Thermoplastic resin molding compositions have now been found which have the required properties and meet the requirements mentioned in that they have a special content of incorporated acrylonitrile and, in particular, a special chemical distribution of the incorporated acrylonitrile.